diff --git a/lib/x11/ext/render.js b/lib/x11/ext/render.js
index cc97876..0758385 100644
--- a/lib/x11/ext/render.js
+++ b/lib/x11/ext/render.js
@@ -8,6 +8,15 @@ var x11 = require('..');
 // TODO: move to templates
 exports.requireExt = function(display, callback) 
 {
+
+        function captureStack()
+        {
+            var err = new Error;
+            //err.name = reqName;
+            Error.captureStackTrace(err, arguments.callee);
+            display.client.seq2stack[display.client.seq_num] = err.stack;
+        }
+
         var X = display.client;
         X.QueryExtension('RENDER', function(ext) {  
 
@@ -19,6 +28,7 @@ exports.requireExt = function(display, callback)
             ext.QueryVersion = function(clientMaj, clientMin, callback)
             {
                 X.seq_num++;
+                captureStack();
                 X.pack_stream.pack('CCSLL', [ext.majorOpcode, 0, 3, clientMaj, clientMin]);
                 X.replies[X.seq_num] = [
                     function(buf, opt) {
@@ -33,6 +43,7 @@ exports.requireExt = function(display, callback)
             ext.QueryPictFormat = function(callback)
             {
                 X.seq_num++;
+                captureStack();
                 X.pack_stream.pack('CCS', [ext.majorOpcode, 1, 1]);
                 X.replies[X.seq_num] = [
                     function (buf, opt) {
@@ -63,6 +74,7 @@ exports.requireExt = function(display, callback)
             ext.QueryFilters = function(callback)
             {
                 X.seq_num++;
+                captureStack();
                 X.pack_stream.pack('CCSL', [ext.majorOpcode, 29, 2, display.screen[0].root]);
                 X.replies[X.seq_num] = [
                     function(buf, opt) {
@@ -119,6 +131,7 @@ exports.requireExt = function(display, callback)
             ext.CreatePicture = function(pid, drawable, pictformat, values)
             {
                 X.seq_num++;
+                captureStack();
                 var mask = 0;           
                 var reqLen = 5; // + (values + pad)/4
                 var format = 'CCSLLLL';
@@ -160,6 +173,7 @@ exports.requireExt = function(display, callback)
             ext.SetPictureFilter = function(pid, name, filterParams)
             {
                 X.seq_num++;
+                captureStack();
                 var reqLen = 2;  //header + params + 1xStopfix+2xColors
                 var format = 'CCSLa';
                 var params = [ext.majorOpcode, 30, reqLen, pid];
@@ -183,6 +197,7 @@ exports.requireExt = function(display, callback)
             {
                 // TODO: merge with linear gradient
                 X.seq_num++;
+                captureStack();
                 var reqLen = 9+stops.length*3;  //header + params + 1xStopfix+2xColors
                 var format = 'CCSLLLLLLLL';
                 var params = [ext.majorOpcode, 35, reqLen, pid];
@@ -217,6 +232,7 @@ exports.requireExt = function(display, callback)
             ext.LinearGradient = function(pid, p1, p2, stops)
             {
                 X.seq_num++;
+                captureStack();
                 var reqLen = 7+stops.length*3;  //header + params + 1xStopfix+2xColors
                 var format = 'CCSLLLLLL';
                 var params = [ext.majorOpcode, 34, reqLen, pid];
@@ -250,6 +266,7 @@ exports.requireExt = function(display, callback)
             ext.ConicalGradient = function(pid, center, angle, stops)
             {
                 X.seq_num++;
+                captureStack();
                 var reqLen = 6+stops.length*3;  //header + params + 1xStopfix+2xColors
                 var format = 'CCSLLLLL';
                 var params = [ext.majorOpcode, 36, reqLen, pid];
@@ -282,6 +299,7 @@ exports.requireExt = function(display, callback)
             ext.FillRectangles = function(op, pid, color, rects)
             {
                 X.seq_num++;
+                captureStack();
                 var reqLen = 5+rects.length/2; 
                 var format = 'CCSCxxxLSSSS';
                 var params = [ext.majorOpcode, 26, reqLen, op, pid];
@@ -302,6 +320,7 @@ exports.requireExt = function(display, callback)
             ext.Composite = function(op, src, mask, dst, srcX, srcY, maskX, maskY, dstX, dstY, width, height)
             {
                 X.seq_num++;
+                captureStack();
                 X.pack_stream.pack(
                     'CCSCxxxLLLssssssSS', 
                     [ext.majorOpcode, 8, 9, op, src, mask, dst, srcX, srcY, maskX, maskY, dstX, dstY, width, height]
@@ -312,6 +331,7 @@ exports.requireExt = function(display, callback)
             ext.Trapezoids = function(op, src, srcX, srcY, dst, maskFormat, trapz)
             {
                 X.seq_num++;
+                captureStack();
                 var format = 'CCSCxxxLLLss';
                 var params = [ext.majorOpcode, 10, 6+trapz.length, op, src, dst, maskFormat, srcX, srcY];
                 for (var i=0; i < trapz.length; i+=10)                                   	
@@ -328,6 +348,7 @@ exports.requireExt = function(display, callback)
 	    ext.Triangles = function(op, src, srcX, srcY, dst, maskFormat, tris)
             {
                 X.seq_num++;
+                captureStack();
                 var format = 'CCSCxxxLLLss';
                 var params = [ext.majorOpcode, 11, 6+tris.length, op, src, dst, maskFormat, srcX, srcY];
                 for (var i=0; i < tris.length; i+=6)